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TROJ_MSIL.AQM

June 30, 2013
 ALIASES:

Backdoor:MSIL/Bladabindi.B (Microsoft); Trojan-FAUE!A98B4C99F643 (McAfee); Trojan.MSIL.Bladabindi.f (v) (Sunbelt); Trojan horse MSIL.AP (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

44,544 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Jun 2013

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Temp%\scvhost.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
8cff24636d2a58810bd5cdc8cb1b8987 = "%User Temp%\scvhost.exe .."

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
8cff24636d2a58810bd5cdc8cb1b8987 = "%User Temp%\scvhost.exe .."

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.496.1743375
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.496.1743406
  • %User Profile%\v2.0.50727.42\security.config.cch.496.1743515

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\8cff24636d2a58810bd5cdc8cb1b8987

It adds the following registry entries:

HKEY_CURRENT_USER\Software\8cff24636d2a58810bd5cdc8cb1b8987
US = "!"

HKEY_CURRENT_USER\Environment
SEE_MASK_NOZONECHECKS = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Temp%\scvhost.exe = "%User Temp%\scvhost.exe:*:Enabled:scvhost.exe"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\scvhost.exe.tmp
  • %User Startup%\8cff24636d2a58810bd5cdc8cb1b8987.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software
    • 8cff24636d2a58810bd5cdc8cb1b8987

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 8cff24636d2a58810bd5cdc8cb1b8987 = "%User Temp%\scvhost.exe .."
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 8cff24636d2a58810bd5cdc8cb1b8987 = "%User Temp%\scvhost.exe .."
  • In HKEY_CURRENT_USER\Software\8cff24636d2a58810bd5cdc8cb1b8987
    • US = "!"
  • In HKEY_CURRENT_USER\Environment
    • SEE_MASK_NOZONECHECKS = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %User Temp%\scvhost.exe = "%User Temp%\scvhost.exe:*:Enabled:scvhost.exe"

Step 5

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\scvhost.exe.tmp
  • %User Startup%\8cff24636d2a58810bd5cdc8cb1b8987.exe

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_MSIL.AQM. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\security.config.cch.496.1743375
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\config\enterprisesec.config.cch.496.1743406
  • %User Profile%\v2.0.50727.42\security.config.cch.496.1743515


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